The present invention is directed to a laser alignment device for sawmills, and more particularly to a device which may be detachably mounted on a lumber cutting machine for the proper alignment of the workpieces.
In sawmill operations, the logs are typically cut about a number of parallel, axial planes to produce a number of irregularly shaped planks, generally referred to as "cants". Generally, the length of the cants depends upon the length of the log from which is it cut, and would be the same for all cants cut from the same log. However, the width of each cant, will vary depending on the particular section of the log which was cut. For example, the cants which are obtained from the central core of the log will be much wider than those obtained from the edges of the log. Additionally, the cants will taper in one direction due to the decreasing diameter of the tree towards its top. Typically, the cants have two parallel, cut faces resulting from the initial ripsawing of the log, and a pair of irregular edges corresponding to the external perimeter of the log. The rounded or irregular edges are referred to as "wane" edges, and are generally removed before finish-cutting the cant into boards of predetermined widths.
For those involved in the processing of the cants into boards, an important concern has been to maximize the recovery of boards from a log or the cant. One way of doing this is to minimize the wane edges which must be removed in order to obtain the board. In the lumber industry, this is obtained by carefully edging the cants along a straight line about the lateral edges of the cants. However, it has been observed that, frequently, it is difficult to determine the exact locations of the saw blades disposed inside the lumber cutting machine, and therefore, it is difficult for the operator to align precisely a cant, to thereby minimize the amount of scrap material removed therefrom.
Conventionally, a light source or the like is used to cast a shadow on the workpiece to indicate the position of the saw blade in relation thereto. However, this method is not effective in a lumber cutting machine in which the saw blades are hidden within the machine, or positioned such that it is difficult for the operator to determine the precise location of the cutting edges of the blades in relation to the board. In addition, where an incoming board-in-motion has to be cut into multiple narrow strips, it becomes critical that the operator know exactly where the board is going to be cut into the corresponding strips. The examples of conventional devices of this type are disclosed in U.S. Pat. Nos. 4,257,297; 4,468,992; 4,503,740; and 4,676,130.
In view of the above, there is a need for an alignment device which assists the operator to align precisely the cants in order to maximize the total useful width of the cant and minimize the scrap material removed therefrom.